The present invention relates to assuring a physician that acceptable eye exams have been acquired. More specifically, the present invention relates to assuring acceptable eye topography exams have been acquired by comparing multiple exams.
Various corneal topography systems and methods are well known and described in the patented arts and in publications, such as Corneal Topography: The State of the Art by Gills, et al., published by Slack, Inc. (1995). The various systems and methods all provide a physician with information concerning a patient""s vision defects. A variety of new topography systems, pachymetry systems, wavefront sensors, and general refractive error detection systems can detect the amount of myopia, hyperopia, and astigmatism, and also, higher order aberrations of the refractive characteristics of the eye.
This vision defect data, assists the physician in determining a patient""s vision aberrations and the patient""s need for and amount of vision correction. The range of vision correction options includes eyeglasses, contact lenses, or intraocular lenses, and various forms of refractive surgery. Refractive surgery techniques include LASIK (Laser-Assisted In-Situ Keratomileusis), PRK (photorefractive keratectomy), ALK (automated lamellar keratectomy), and LTK (laser thermal keratoplasty). All of these techniques aim to provide permanent vision correction.
In the event a LASIK procedure is desired, a physician or more likely a laser system develops an ablation profile for each patient""s eye. The ablation profile defines the amount and location of corneal tissue to be removed from the patient""s eye by the laser system. Laser surgical treatments have become progressively more refined, allowing more subtle defects to be corrected. Myopia and hyperopia can now be corrected to a high degree of precision with current techniques, and using excimer lasers, higher order defects can also be corrected, such as irregular astigmatism.
With the advance of refractive surgery, a fast developing area is what could properly be called xe2x80x9ccustomized ablationxe2x80x9d. Customized ablation is where a LASIK or other refractive procedure is performed based upon an ablation profile generated for each individual patient""s vision defects. It is believed that this customized ablation will result in better results for the patient than have been known in the prior art and will also significantly reduce the number of poor results. An example of a system employing a topography system in conjunction with a laser to generate an ablation profile is described in U.S. Pat. No. 5,891,132, entitled Distributed Excimer Laser Surgery System, issued Apr. 6 1999.
The accuracy of prior art exams has been determined by visual inspection of one or more exam by a physician. Another tool used in the prior art to assist the physician in choosing an exam to use is a difference map. A difference map is a graphical map showing the difference between to exams. The physician can then look at each individual exam and the difference maps to determine what exam, if any, to use for further treatment.
In preparing these customized ablation profiles, the topography data and other vision defect data will be heavily relied upon. Therefore, a need exists to assure that the data relied upon are accurate.